<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title></title>
    <script>
    let arr1=[{a: 12, b: 5},2,3];
    let arr2=JSON.parse(JSON.stringify(arr1));

    arr2[0].a++;

    console.log(arr1);
    console.log(arr2);
    </script>
  </head>
  <body>

  </body>
</html>
